This is part and parcel f building a PC, all builders even us more experienced have problems, so don't worry hopefully we will get you through it.
My first thought is a possible RAM issue, compatibility can be a major issue as I have found out recently.
If you have Windows still installed remove a couple of sticks and see if it will boot.
If it does insert another stick and try again.
Post back, by the way it will be a nice build once you get it going.