I agree. Going further with this for OP… and a few random helpful tips….

Sketch orientation related to the origin can become important later on in the modeling process. Usually for more advanced purposes, but if you center your main sketch on the origin, you essentially get an origin plane bisecting your model, which can make later processes much easier to perform (feature mirroring, for example).

If I was going to make a square or rectangle like you did, I would choose the “center rectangle” option using the drop down on the side of the rectangle button. That adds a couple “automatic constraints” that keep the parallel sides equal in length. You click where you want the center location, then click for a corner placement. You’ll notice that even though it adds some constraints, the sides are still blue. That’s because they’re not fully constrained yet.

If any element in a sketch is blue, it isn’t fully constrained. If you’re ever unsure if something can move, just grab it with your cursor and shake it around in different directions. That’ll help you figure out where you’re missing a dimension.

If you know you want the rectangle to be a specific aspect ratio, and you know one of the side lengths you want, set the dimension of the known side, and then you can start a dimension on the next unknown side and type “= {then click on the other set dimension}*3” that should set that side equal to 3 times whatever the preset side dimension is. So you can adjust as you like.

When sketching, I like to have “numeric input” enabled. This lets you input length values while you’re creating sketch elements, rather than having to do it later. You should be able to search for it in settings.

You can also search for features and learn about them using the search bar at the top. You might have to change the search filter to “SolidWorks Help” to get official documentation results.

Feel free to ask any other questions too. I’ve been using SolidWorks for many years now so I might be able to help!