How to upload document from one document library into another document library

public void UploadChart()
{
try
{
String GenerateNo=”ABC_0001”;
String Vertical= Request.QueryString["Vertical"];
sourceWeb = mySite.OpenWeb();
destinationWeb = mySite.AllWebs[Vertical];
destinationWeb.AllowUnsafeUpdates = true;
destinationWeb.Update();
sourceDocuments = sourceWeb.Lists["List Template Gallery"];
destinationDocuments = destinationWeb.Lists["Chart"];
currentSourceDocument = sourceDocuments.Items.GetItemById(25);
fileBytes = currentSourceDocument.File.OpenBinary();
fileNameandExtn = currentSourceDocument.File.Name.Split(".".ToCharArray());
NameofDocument = fileNameandExtn[0] + "_" + GenerateNo + "." + fileNameandExtn[1];
ht1 = new Hashtable();
ht1.Add("ContractNumber", GenerateNo);
//GenerateNo is the method to generate number
relativeDestinationUrl = destinationDocuments.RootFolder.Url + "/" + NameofDocument;
destinationFile = ((SPDocumentLibrary)destinationDocuments).RootFolder.Files.Add(relativeDestinationUrl,fileBytes, ht1,OverwriteDestinationFile);
destinationFile.CheckIn("New Contract", SPCheckinType.MajorCheckIn);
}
catch (Exception ex)
{
//System.Diagnostics.EventLog.WriteEntry("Contract Details Exception", ex.Message);
}
finally
{
mySite.Dispose();
}
}

How to upload document into document library using C#.Net

String Continent = clistitem["Continent"].ToString();
fStream = FileUpload1.PostedFile.InputStream;
fStream.Read(contents, 0, (int)fStream.Length);

fStream.Close();

//storing the contents of the uploaded document
Bytes[] contents= new byte[fStream.Length];
fileName = FileUpload1.PostedFile.FileName.Substring(FileUpload1.PostedFile.FileName.LastIndexOf('\\') + 1);
Hashtable ht = new Hashtable();
ht.Add("Continent", Continent);
SPFile fff = files.Add(fileName, contents, ht, true);
myweb.AllowUnsafeUpdates = true;
myweb.Update();

How to loop through all the Groups

foreach (SPGroup grp in myweb.Groups)
{
if (!grp.Name.Contains("Admin"))
{
foreach (SPUser user in grp.Users)
{
lbUsers.Items.Add(user.Name);
}
}
}

How to find one list item from the Listitems

SPDocumentLibrary ContractsLib;
SPListItemCollection contractsItems;
ContractsLib = (SPDocumentLibrary)myweb.Lists["Contracts"];
SPListItem clistitem;
String EmployeeNumber=Request.QueryString["EmployeeNumber "] != null)
{
SPListItemCollection contractsItems;
String strContractNumber = Request.QueryString["ContractNumber"];
ENumberQuery = new SPQuery();
// Belowed one line of code will help you to loop through all the items;
ENumberQuery.ViewAttributes = "Scope=\"Recursive\"";
ENumberQuery.Query = "" +
" + "\"ID\"" + " />" +
"" +"" +"" +" + "\" EmployeeNumber \"" + " />" +
" + "\"Text\"" + ">" + strContractNumber + "" +
"" +
"";
contractsItems = ContractsLib.GetItems(ENumberQuery);

clistitem = contractsItems[0];

How to connect MOSS(Sharepoint Server 2007) using c#.Net

Add Microsoft.Sharepoint.dll as a reference in your Project.
Use the following namespace for your Project to utilise the Sharepoint classes, properties and methods.

using Microsoft.SharePoint;
using Microsoft.SharePoint.WebControls;
using Microsoft.SharePoint.Utilities;

Once you add the reference and namespace properly, intellisense will show you all the classes and methods properly.

mySite = new SPSite("http://Test-Sample:123/"); //You have to specify your site here.
SPWeb myweb = mySite.AllWebs["IT"]; //You have to speify the subsite here.
myweb.AllowUnsafeUpdates = true; //It will allow you to update listitem or List or anything from your code.
myweb.Update(); //It will update the web.

This code will be hardcoded. If you don't want to hardcode you can use the following code snippet

string Subsite = Request.QueryString["Subsite"]
mySite = new SPSite(this.Page.Request.Url.ToString());
SPWeb myweb = mySite.AllWebs[Subsite];
myweb.AllowUnsafeUpdates = true;
myweb.Update();

The above example is a good practice to implement it to your Project. In this project instead of subsite hardcoding, i used querystring to fetch the subsite from other forms. Based on the subsite value it will connect to your subsite.