Hi Tbish,
Welcome to ALR. There's a lot to consider when deciding on a first build. What do you want to do with the gun when it's finished? Target shooting, hunting, re-enacting? Rifle or smoothbore? Is there a time period/style of gun you like? Do you have any woodworking and metalworking experience? Own any tools or reference books?
There are several companies offering quality kits, and components, all the way from a plank and parts to nearly finished, once you figure out the above questions. Good luck, but be forewarned, gun building is fun but addictive.
-Ron