Ingame, if I wanted to make a new 'line', so-to-speak, how would I do such?

winset(player,"label1","text=blahblah\nblahblah") doesn't work
The forum search would've answered this question; another person had an identical problem before.

When using the "params format" (e.g. in winset()), you can't use special characters (such as special symbols and newline characters) intact, as the format doesn't support them as-such. Instead, those characters have to be specially encoded when included in the format. You can do this automatically by the means of the url_encode() proc (params2list() also implicitly does this, among other things).
However, in this case, you don't have to use winset() in the first place - you can just use the output() proc, which doesn't use a special format, to output to the label.