Since monday, I'm having the possibility to work with a midi keyboard. That's way faster and if you buy for example one made by Native Instruments, you get tons of synths, basses, and many other things for free. However, I had this exact problem before and here are two things I did.
Note that both of them are going to require you to have a lot of patience, and none of these will give you the best experience, but I still recommend you to get a midi keyboard you are seriously considering to go deeper into music making.

1. Possibly the worst one, your choice of a sound editor and your choice of instruments.
When I was interested in music making for the first time, I seriously used this method. I set my sound editor's input, at the time it was Audacity, to windows wasapi, and the output to my headphones and there you go. I recorded everything using the soundcard in my laptop. Of course I couldn't equalize this way, I couldn't even separate tracks because at the end it was only one huge track. I can show this method to you in action, but it isn't the best, I warned you.

2. Probably the better one, using reaper and VSTs of your choice.
After I got enough of the first method, because it was too much of a hassle for me, I sterted to do this. The disadvantage of this one is that your laptop is too small for producing anything, so either you must think a lot before recording or your hearing must be very good to be able to separate everything and record all the parts in a different track. It's horrible if you don't have the required patience. And for this you must find a lot of VSTs, there are a lot of free ones on the internet though, I also need them because of my midi keyboard so I need to do the same.

If you'd like, reach out to me in private, and I'll try to do my best to help.

There's also a neat little synth that runs natively in your web browser. You'll find others, but this is the one I was personally refering to.