How to pass ID from one page into another page in c#?

Hai friends,
i need to display the details depends on the request_id in page. if i save the content ll show on second page.........

1)default page is login when the ppl logged in redirect into ==> 'travelreq.aspx'

2) travlreq.aspx page contains 2 asp pannels when the users fill first pannel request_id ll be generated,
depends upon that request_id pannel 2 details ll store and show on gridview. when pressing ADD.

3) After finished the details users gave the save ll goes to HOME.aspx page in travel Draft.

4) if i choose the link button entire aspx ll shown of what i have saved on my "travelreq.aspx"
in viewdetails.aspx.

i need 2 requirements

1)in travelrequest.aspx page as before u told declare global variable for request_id
depends upon that id show values what ever dates are stored i m entered in that on gridview's.

2) after save the content entrie details ll show on viewdetails.aspx page here also users can add such values (i.e when we kept the draft mail after include some texts and submits it contains new text and saved contents also)
that present values also show on gridview?

here also gridview ll show on request_id?