If you're wanting to learn how to prepare and send a package with USPS, there are some things you need to know. That way, when you have anything to ship, you can do it properly. Here are some tips that will make this process a lot easier to deal with.
Figure out what you're going to ship the package in so you know what materials you're going to need to get. Generally, you're either going to ship something in a box or a bag of some kind that is made for shipping. There are boxes you can get from the post office but if you don't want to go that route you can always look for a box you may already have. Just make sure that you're using packaging that you can affix a label to and that doesn't already have old labels on it that you haven't gotten rid of yet.
Once you have some kind of a box or anything else to ship something in, you're going to need to get some bubble wrap or other packaging like packing peanuts to place around what you're shipping to keep it safe. You want to make sure you use ample amounts of packaging so that your item isn't likely to break on its way to its destination. You can generally find packaging at a local big box store or somewhere similar. Keeping an item safe is important because you can't really control how the package is handled after you drop it off.
After you've put everything together you're going to need to tape the box up so that it doesn't open while it's being handled by the USPS. It's generally better to use more tape than you need just to be sure that everything is going to be secure during shipping. They make packaging tape that is mainly for this kind of thing, so look into getting it. You're probably going to be able to find it at the same place as you got your packing materials. The USPS sometimes has tape you can use with their special boxes so look into that if you don't have any tape on you when preparing a package.
Speaking of special packaging, there are other options at your local post office you may want to look into if you want to use something like a flat rate box. Basically, a flat rate mailing box is something that you can put anything into and it will cost one fee no matter how heavy the package is. This is good if you have to ship something that fits in the box and that would be expensive to ship any other way. You can also use custom boxes for shipping, which has a lot of benefits as well, learn more about that here.
Know that you can't ship anything you want in the mail because there are a few things that the USPS is not going to want for you to ship. They are going to ask you, for instance, if there is anything that is hazardous in the package when you're going to mail it through them. It's best to look into this before you head to the post office so you don't find out when you get there that you can't ship something. Before you ship anything, go to the USPS website to view an updated list of what's allowed and what to avoid.
Figure out how you're going to pay for shipping so you can determine what you're going to have to do to get a label for your package. For instance, you can sometimes print out postage through a PC at home if you want and can pay through the internet from home. Then, you can print out a label and tape it or glue it to your package so that you then just have to take it to the post office and drop it off. You can also just pay for shipping when you're at a post office which is easier if you don't have a printer available or nothing to affix the label to the package with.
Learn what the various shipping options are so you know what to send your package as. For instance, if you have something that needs to be sent to someone quickly, you're going to want to use something like Express mail which is faster than something like Priority. If you're in a rush then it's generally going to cost quite a bit more than the slower options. You can use the USPS website to figure out what pricing is like so you're not surprised by what it costs if you go to the post office to pay for shipping something.
Once you know how to prepare and send a package with USPS, you can get started. In the end it's easy to learn once you know what you're doing. Just take and work with what you learned here and the next time you need to ship something, you'll know what it takes.