In general, code requires very strict formatting, so you should look at the tutorials and follow them exactly. It’s very important that no code can have two meanings, because the computer would have to pick one basically at random.
Here, the command to set a variable to a fixed value has three parts:
1.*set, to indicate you’re setting a variable
2.the name of the variable you’re setting
3.the value you’re setting it too
Then generally you want to end the line to signal you’re done so the computer knows not to look for a + and another value; you might be able to get around that using parenthesis but I haven’t checked because I’d recommend not doing that.
There’s multiple different ways to structure *set for different tasks, but they’re all equally strict. If you’re getting errors off a line right away it generally means you’ve made a mistake in following the rules for what you’re trying to do so that the line doesn’t match any rules and thus means nothing to the computer. You’ll probably solve it faster by going to the relevant wiki page and finding the example code for the thing you want to do then duplicating it rather than asking on the forum. These sorts of errors are pretty much like screwing up punctuation in prose; they happen all the time and are usually easy to fix if you check reference material.
Now, if that doesn’t help, or worse, the computer accepts a line but doesn’t do what you want it to, take that to the forum. Also, while error messages are useful don’t rely on them to be perfectly accurate; they’ll come at the point where it’s definitely impossible for the code to mean anything and may be some distance from the mistake.