What we usually advise beginners is get everything else first, then get a pack that will hold it all. But, since you have the pack already, not to worry. The tent can be tied to the outside of the pack in most cases. Not sure about your pack, but someone with one can tell you how to do that. Same for pads and sometimes for bear canisters if you are carrying one. (Don't worry about a bear canister for the moment, focus on getting the rest of your stuff.)

If you let us know where you will be hiking and what time of year, and kind of weather you will encounter, we can suggest other items.

Look at the gear lists linked from the main page of the site (not the forums, the main page of TLB itself) to see typical items for different applications. Also look as some of the vendors who offer a lot of different stoves, bags, etc.

DON't buy stuff willy nilly just because it looks cool or someone else here has it. Backpacking involves building a system where everything works together-clothes, shelter, cooking. Buying stuff at random will do nothing but load up your closet and keep you busy selling unwanted gear on eBay.