I don’t know of a website, but it’s really not that difficult.
Right side rows are read right to left, wrong from left to right (or just purled across if not shown at all.)
Each box represents one stitch of the finished row. For example, a yo is just the yo, a k3tog is represented by one box because that’s what happens when you k3tog, any stich combo that results in more than one stitch covers the number of boxes of the result of that. The key with the pattern tells you what to do for each symbol.
Anything else? Oh yeah! If there is an area that says ‘no stitch’, then just do whatever is in the next stitch box.