We are a little confused about framing. Let's talk it out.
1) TAKE IT TO THE PROS
The EASIEST way to frame is to take it to someone who knows what's up with framing. They will make sure your art is safe and sound for generations to come. They will have good ideas and wise advice. However, they are paid for that wisdom. This option is the easiest, but it is the most $$$
If your art piece is a standard frame size it might not be that expensive. But as soon as you dip into custom frames the price goes way up.
My favorite (PNW local) framers are Museum Quality Framing. They are super smart. They also have some more affordable options I've taken advantage of. My advice when going to the pros: ask lots of questions and don't be afraid to ask about cheaper options. They want to help you.
You can make your own frame and cut your own matt. You can do it! But it's labor intensive. It's a life style choice. You can also make your own frame and then get someone else to cut you a custom mat. HERE's a helpful video on it (she doesn't have the ideal everything which I think is relatable and helpful). If your art work is on a wood panel or canvas you'll need a floating frame. See HERE on how to make a floating frame.
3) PURCHASE + ASSEMBLE
See HERE for this option.
This is always an option. It is probably the most common and is the most middle of the road as far as money. Search through resources such as: Amazon, Hobby Lobby, Michaels, Etsy, Target, Walmart or TJ Maxx or a garage sale to find a frame you like. Buy a frame that is bigger than your art piece.
You'll need a mat (that piece of mat board that surrounds and protects your art). If your art is a weird size you'll need to get a custom mat. Hobby Lobby, Michaels , or a pro shop will cut a custom mat for you. Don't be tempted by the pre-cut mats at the craft store, they are never the size they claim.
Important Note: When you are searching for a frame, pay attention to the listed size. If it is a "16x20" frame" that most likely means the frame is 16x20" and the art that goes inside should be 11x14" or something (depending on your mat). If your print is 16x20" you should get a frame that is larger than 16x20" (such as 20x24"). Some frames are labeled well and they say "matted for: ____" But others will be more cryptic. Think it through before you purchase.
After you've got your frame and your mat, you are ready to assemble. See HERE for more information on that.
OR you can take your pre-purchased frame and the custom mat to the pros (or hobbly lobby/michaels) and have them assemble it for you. I highly recommend this because they have experience and that way you don't have to buy all those extra supplies.
Hanging framed art is a different topic. But here are some videos to help you out!
THIS video is about adding wire to the back of your frame.
THIS video are some hacks on how to hang the frame.