You have to get quiet and think about what would be significant to you to do. We could not attend the funeral 3 days away for a friend, so we floated a (bio-degradable) wreath down the river with a single blood red rose. I am sorry for your loss. Grieve when it strikes, then go on. It never ends but it gets easier to continue on living.
Sometime when you're alone, have a conversation with them, you need to speak out loud, they can't read your mind, tell them you love them, and say goodbye, but if you want, sometimes their spirit will stick around. It can be fun at times
Just remember them, visit their grave, talk to them, think of the memories. Years back my best friend and I had a bit of a falling out, years later he was killed, I missed his funeral and everything. I always thought of him, always wanted to fix it. After he passed, I visited his grave, I spoke to him sometimes, still do. One night i had a dream, I dreamt he an i had met at this little cafe and just talked and caught up on our lives, it was so realistic. It was like a memory not a dream, I woke up smiling and happy that I'd gotten to reconnect with him, then I realized it wasn't real, and he was gone. To me that dream was real, I finally got to resolve our issues and say my goodbyes and let him know how I missed him.