Welcome to the Learn Dothraki website!
Dothraki should not be too hard to learn. Many Europeans are multilingual to start with (and you know a fair bit of English, it seems), and that always helps when learning additional languages.
Look at the materials in the 'getting started' section. Also read the materials on the wiki regarding grammar, etc. Probably the biggest challenge is there are a number of tables that show how various inflections work, as well as pronouns, adjectives. These have to be memorized. But once you have these solid, the rest should start to come easily.
You also have your choice of the wiki dictionary, or the downloadable, printable dictionary for learning vocabulary. Both are kept up to date.
You can also check out David Peterson's Dothraki blog at
www.dothraki.com and join us on an IRC chat we currently have every Monday evening at 7 PM Pacific Daylight Time (GMT +7 hours)
Enjoy!