You'll be best off buying some bolt down metposts and some anchor bolts, just bolt them into the concre
If your just going to birdsmouth the trusses to the wall plate and it's 15 foot long you'll need to put supports in the middle of the wall to stop the roof sagging, also remember if it's a pitched roof you'll need to brace it across to stop the roof pushing the walls out in the middle. a 6x2 every meter if your not walking/storing stuff up there, every 40 cm if you are.
alternatively you can make roof trusses on the ground with the bracing already on them and lift them on, just make one and use it as a template so the following ones are the same.
have a look at this see if it helps,
www.essortment.com/yourself-build-garage-11994.html although I never have and never will build a wall on the ground then lift it in place as I personally find it much easier to build in place.