Hi and welcome!
In addition to Skyder's thorough introduction, and in reply to some of your additional questions:
I only have one problem--I'm on Mac, and cannot afford a PC at the time being. Is there any paint application/website that will do the same thing and is compatible with Mac?
Looks like
the GIMP has a Mac OS-X version. It is a fairly potent 2D graphics platform, comparable to Photoshop for a beginner user. If you're looking for something simpler, I can't help much further, being completely unfamiliar with the Mac platform and applications.
And also, in the tutorial you linked me to, I have a question. What if I want to make one of my own personal designs in Shipbucket format? I (think) have the basics of it, and I might make a small monitor just to get started. But I do have a bunch of my own designs that I want to upload to Shipbucket. (not all of them are hyper-realistic).
Best thing to keep in mind is to stick to the
templates. They are fairly self-explanatory, just pick the size best fitting your drawing (don't forget to leave space for the title), follow the instructions and remove the orange text and markings afterwards.
Please post your creations to the
beginners' section at first until you can work out the style, then the next "normal" fictional ship drawings go into the
Personal Designs folder as long as they qualify as ship material, while those that have no hope of fitting the Shipbucket guidelines due to content or style should be posted to the
Non-Shipbucket Drawings folder. Give a look to the different sub-boards to get a feel of what goes where.
Oh, and another question, how do I "copy-paste" turrets, boats, and other parts from the parts sheets?
That's a very generic question that hinges a lot on the image editor you use. As a rule, select and copy the part of the original image that interests you, paste (preferably in a new layer) and move to the right position on your image to be edited. Pay attention to the transparent background color in your selection, but how to do that exactly depends on the software you use. Or am I missing a more specific aspect of the process?