Thank you for all your comments so far. So it looks like I need to learn radicals to learn to write... So in order to learn the radicals, am I supposed to just learn random ones and memorize them, and keep learning more? Is there any way to combine them? How do I do this?

Chinese characters are really special with using hieroglyphics. First, you need to learn some radicals, and these radicals compose all the characters. How to learn radicals? Because Chinese is kind of hieroglyphics, so using picture to memorize is a good way to learn these radicals. Then all will be on track. And you will get one more benefit when you learn the radicals well, because a lot of characters pronounce just as the radicals do, and even Chinese people pronounce the radicals when we don't know the characters. Hope this can help.

Are you planning on writing characters by hand, or do you just intend to write using a computer or phone? If it's the latter, you only need to be able to read characters and then select them after typing their Pinyin. If it's the former, you just need to spend a lot of time practising writing out the characters. Either way, I recommend you start by memorising the most common radicals (the parts that make up a character). For example, it's much easier to remember 想 if you know the radicals (eye (目), tree (木) and heart (心)) than it is to remember it stroke by stroke.

You can choose a Chinese language textbook for learning.