Where can I get the tools?
You can either install full Visual Studio 2010 and update it to Service pack one first. Or just go straight for the download from: http://create.msdn.com. This will install the latest SDK (7.1) and includes Expression Blend for Windows Phone, which will allow you to quickly design and create your application without the need to know how to program thanks to SketchFlow!

Tools are installed, now what?
You can easily dive right in to developing right away if you're familiar with Silverlight, or there are many resources available out there for introducing you to it.

One of the tutorials I found most interesting, in depth, and easy to follow was the series of Windows Phone 7 Jumpstarts on Channel 9.

I wrote a few blog posts a while ago for some quick reference to WP7 development. I haven't had a chance to test these lately with the release of Mango, but I believe the principles are the same. I also apologise for the formatting issues, but if you click the pastie number to the left of the 'raw' button you'll hopefully be able to view it more easily.

What is the Silverlight Toolkit?
The Silverlight toolkit is something that includes WP7 controls, which are not, by default, in the SDK. Now, although it is possible to create your own custom controls through the power of Silverlight and Expression Blend, it can be tedious to do so - and knowing that there are already some controls available it makes sense to use them.

How do I use it in a project?
  • Add resource Microsoft.Phone.Controls.Toolkit
  • Create folder: Toolkit.Content
  • Add images into "Toolkit.Content" from: "Program Files > Microsoft SDKs > Windows Phone > v > Icons > dark"
  • Mark images as Build Action = "Content" in the properties window
  • Rename them to something like: ApplicationContent.Cancel.png for them to automatically load into the phone, and to change color depending on the user's selected theme.
Students make money, for free!
If you're lucky enough to be a student then Microsoft have an awesome portal, which also contains links to downloads and tutorials called Dreamspark

Once you sign up and get verified you'll be able to activate your student developer account, which allows you free submission of 100 Applications on the Marketplace! Any money you make as a result of this, is yours, and you haven't paid a thing for it!

A lot of people have ideas for mobile applications but don't take the first steps to turning that idea into reality. Now you know that you can do it for free, and make money. What's stopping you?