You can get a start on things with a very small tool kit. It's not ideal, but you can make due for a lot of it with an adjustable wrench and a set of metric allan wrenches. It's always best to buy good tools, but inexpensive tools can get you by in a pinch, but they sometimes break. You buy a good tool once, use it for life and pass it on to the next generation.
We can help support you here on the forum. State what you want to pull apart first, we'll chime in with what tools you'll need and some how-to. There is a wealth of info on Sheldons site, but don't forget the Park tools website, and my current favorite resource: Bicycle tutor
www.bicycletutor.com The reason I mention bicycle tutor to folks so often is because they have really easy-to-follow videos that explain and show what to do. You can buy tools over time as you go along from task to task.