Now, regarding knot-tying. Sailors, Boy Scouts, and other types of person have come up with literally thousands of different ways to tie a knot over the centuries. If you really want to learn about the subject, a grand old book called The Ashley Book of Knots, by Clifford Ashley, will tell you more than you'll ever need to know. But knot-tying doesn't need to be a form of witchcraft. The truth is that (though some ship modelers don't like to admit it) to rig a ship model you only need to know two knots: the half hitch (and its close relative, two half hitches) and the clove hitch. They're just about the two easiest knots to tie.
Several websites offer nice, animated illustrations for knot-tying. Here are links to two - from the same site. (If you go to the homepage, you'll find illustrations of lots more, but let's just stick to the basics.)
Here's the half hitch (and two half hitches: http://www.netknots.com/rope_knots/half-hitch . This knot will work for at least 90% of all applications on a ship model. You probably already know how to tie it, and didn't realize you did.
The clove hitch has one common use in sailing ships: tying ratlines to shrouds. Here it is: http://www.netknots.com/rope_knots/clove-hitch . Where the text refers to a posts, substitute shroud. Some people, for some reason, find this one difficult. I've never been able to figure out why.
A couple of others may come in handy occasionally. If you can handle a third one, I'd suggest the square knot (known more often to sailors as the reef knot) for tying two lines together: http://www.netknots.com/rope_knots/square-knot . The slip knot comes in handy sometimes for tying a line off to a spar; it lets you make a big loop and tighten it. It's actually just a variation on two half hitches: http://www.netknots.com/rope_knots/slip-knot . I remember having to learn it to tie my neckerchief in the Cub Scouts.
Every half-baked sailor knows how to tie a bowline, but it comes up in ship modeling so seldom that I have to look it up every time I want to tie it.
Best, maybe, to practice with some real rope (you'll only need a couple of feet) first, rather than starting out with the thread you'll use on the model.
Bottom line: if you can tie the two half hitches and the clove hitch, you can rig a ship model.
Hope that helps.
Slight disclaimer: the labels for these knots sometimes get kicked around a little. I'm using the ones used by that particular website.