how create session & what's use of session

how can find out substring in a string

how can find out the last value of table

what is Ajax?I want to use the technology in image control

if we want to send a image in a folder which is in my project on clicking a button after selecting a image from any directory in my computer through fileupload web control?

Is it necessary to install asp.net on that computer on which a deploy project of asp.net is installed.and if it is a web application then how we get domain for it and a perticuler site name.

i need to show image when the user select path. ie, the file could be at any location. at the time of execution user can give any path in the textbox. and at the same time when selection is made by user in textbox the image immediately should show in the picture box. i use this code protected void Page_Load(object sender, EventArgs e) { Image1.ImageUrl = TextBox.Text; }

Image1.ImageUrl = TextBox1.Text; //textbox receive path of the image for example textbox=c:\Blue hills.jpg; //but image is not show in the image control

i am using controls 1- image control 2- file upload i try to upload a file in image control that display in image control as the file uploaded. and save it in database on submit button event

how can select any control at the run time when click on this control