I probably cannot help but do you have guides enabled? I do not do web stuff but on what I have I have rulers enabled and can then pull the guides, and look in widows drop down and make sure there us a check mark for show guides. If you are in the guides layer then any line you draw will be the red dotted guide lines. to draw regular lines make a new layer so long as it not a guides layer then from there you can draw normally and snap to guides. Does that help?