Any SharePoint Development requires you to develop your Web Part and deploy it to sharePoint,in this post i will describe the steps required to deploy your web part to sharepoint 2007 site:
1) after creating your web part,you have to sign it with strong name.
To Do that : simply open the project properties and on the signing tab select new and then save the properties ad build your web Library.
2) add to the GAC on your sharePoint Server.
you can do that by using VS.Net Command tools or use .Net 2.0 configuration Tool from the control panel.
NOTE: after you add your DLL to GAC you can find it on C:\Windows\Assembly Folder.
Take Note : you have to store the Publick Key token of the signed DLL by right click on your DLL -> Properties and save the public key token on a notepafe file because it will be used later.
3) To add this webpart to a sharepoint site,you have to make it "Safe Control " to be loaded and configured on your site.
To Do that : open the web.config file of your site,it resides on C:\IntePub\WWroot\WSS\Virtual Directories
then open the folder of your site,it takes by default the port number of your site.
Paste this code on the web.config : (i removed <> letters of the key)
Safe and close your web.config.
4) open your sharepoint site->site settings->web parts->click on new and select your webpart and then click on Populate Gallery.
5) then click on any page and add your web part.
Hope this helps.