Sharepoint  Code:

WebPart: Creating a Sharepoint Web part (With User control)

Brief: Create a ASP.Net WebApplication and Create a User Control in it.  Drag This User Control in Sharepoint WebPart Applicaion(project).Finally Deploy the Web Part in Sharepoint. For Details click on the WebPart Link Above

Sharepoint Lists: Populating a DropDown Control with Sharepoint List Data

Brief:  Using GetDataTable Property of Sharepoint Lists, Retrive all List Items in a DataTable, and add the Table in a Dataset. Finally,Bind the Dataset and Table with the DropDown list. For Details click on the SharepointLists Link Above

Adding Documnets in Document Library

Brief: By Creating a ASP.Net file uploload contol and a submit button. You can add the documnets directly into document  library by using SPFile class. For Details/Code click on the Adding Documents link Above