Public Sub CheckOut

Dim instance As SPFile

instance.CheckOut

public void CheckOut ()

Dim site As SPSite = SPContext.Current.Site
Dim targetWeb As SPWeb = site.AllWebs("Site_Name/Subsite_Name")
Dim docLibFolder As SPFolder = targetWeb.Folders("Shared Documents")
Dim docLibFiles As SPFileCollection = docLibFolder.Files
Dim i As Integer

For i = 0 To docLibFiles.Count - 1

    docLibFiles(i).CheckOut()

Next i

SPSite oSiteCollection = SPContext.Current.Site;
SPWeb oWebsite = oSiteCollection.AllWebs["Site_Name/Subsite_Name"];
SPFolder oFolder = oWebsite.Folders["Shared Documents"];
SPFileCollection collFiles = oFolder.Files;

for (int intIndex=0; intIndex<collFiles.Count; intIndex++)
{
    collFiles[intIndex].CheckOut();
}
oWebsite.Dispose();