Look up ritual outlines online to find a basic format. You really don't have to bring pictures of the departed at all, though some people like to. You could also bring something that belonged to the person or even a memory to share in words. It's also the end of the year to Wiccans (from Celtic ways of doing things), so it's common to release anything that is no longer helping you to make way for the new.
One answerer mentioned tales of valor as the theme, which is only true in certain areas. In the northern European countries, this was more common and modern Asatruar still celebrate their feast of the dead with this in mind, that it is about fallen warriors and tales of valor.
He was also completely incorrect in his interpretation of pagan celebrations of the death being rip-offs of Christianity. Quite the other way around, in fact. All over the northern hemisphere, celebrations and remembrances of the dead were held at the end of summer, when it was obvious that the whole of the earth was "dying." The Celts celebrated Samhain, the Northerners celebrated Einherjar, the transition of Persephone from her summer home to her winter stay in Hades, all these and more were celebrated around the time when the constellation Pleiedes rose in opposition to the sun's set, which now occurs in early-mid November (it moves by a few days every few thousand years). The calendars were lunar, yes, but they were first based on the greater celestial events, then the solar events, then the lunar, then the earthly events. So the celebration of Samhain, for instance, would have been around the time when the Pleiedes were opposite the sunset, and the nearest full moon to that would have been the time for greatest celebration. If the weather or timing of important agricultural events happened earlier (say you had an early frost and had to move your cattle to their winter fields earlier than expected), you would celebrate earlier than when might be appropriate for the celestial events. Since the cattle moving between their winter and summer pastures was a major part of the events of Samhain (and Beltane), if you needed to move them at a different time than what the stars said, you did it and moved your celebration accordingly.
Samhain IS the Celtic new year, as in Celtic belief (as in a lot of indigenous beliefs), new life begins in dormancy, in darkness, in the gestation that precedes life. The child is first in the darkness of the womb, the seed gestates in the dark earth, the new year begins its existence in the darkness of the year, the new day begins with the end of the last (sunset), your achievements in life begin as seeds of thought in the darkness of your mind, etc. In this thinking, the beginning of something happens in the darkness, so the new year begins at the end of things from the old year, which would be at Samhain, when crops are dead or near dead, when the light is dying, etc. This is also why many celebrations in modern Wicca and Celtic neopaganism begin the night before the actual day, as we would see it. Yule begins the night before the solstice, Samhain happens the night of the 31st (because it's actually on Nov 1st), same for all the others. We can move the dates by a bit, to make for convenience of schedules and happenings in our lives (just like the old Celts did), but we try to make it begin at night if appropriate or in the morning, if that is appropriate. It can be a good practice to celebrate with ritual and feast in the evening before a specific holiday, then awake early (or stay up all night) to welcome the new day being born, along with any works you did in the ceremony, for they too were planted as seeds for the new day/season/year.
As for your specific questions about how to do it "simply, safely, and in a fun manner," that is totally up to you. The only real safety issues will vary depending on whether or not you're using candles, fireplace, bonfire, no fire, etc. Use common sense, if you're using fire have a fire extinguisher around. If you have incense, don't burn things that are toxic (just buy an incense if you're going to use any, until you can learn how to make you own if you want to do that). Simple is easy, just find a good ritual outline (doesn't have to be Samhain-specific). You usually cleanse the space, cast a circle, call the directions/elements, call any deities or spirits you want to attend, state the purpose of the gathering, do whatever work you want to do (asking for the blessings of your beloved dead, releasing all things that are no longer helping you in life, etc), eat your ceremonial cakes and ale if you have it, thank your beloved dead for coming and say goodbye for now, thank and dismiss the deities/spirits, close the directions/elements, uncast the circle, ground and eat something. As for having fun, you could tell fun stories of the deceased, you could sing or dance, lighten it up a bit, etc.