How do i connect or what is the easiest way to connect from laptop to my N900 through wifi.

by creating ad-hoc network can v transfer files?
but am not able to do so.
Hope there is a application.

You're asking two separate questions, there. Are you asking about wireless network modes and establishing a connection, or what software to use once you have?

You can certainly transfer files over an ad-hoc wireless connection using any number of programs including scp, rsync, rdiff-backup, curl, wget, etc, or you could even turn the N900 into an access point and connect the laptop wirelessly to it, have it run a SMB server...

Why you'd want to is anybody's guess... my N900 connects to a conventional AP run by a conventional router and talks to my other devices over SSH. Describe your use case and someone may be able to recommend appropriate software,,,

actually my question was about connecting to n900 through wifi and transfer files through it. I was not able to actually.
Both from n900 to pc and vice versa.

now that u have named some programs let me try out.

Your guess is right i did not want that actually.

Unless you have some highly specialised requirement, then the usual way of doing this is to connect your N900 to an existing wireless network run by your router/access point. When your N900 has an IP address on your home network, and you can ping it from your computer, then it'll need some kind of software installed for remote access - I use ssh, and over that you can use scp to copy, sshfs to mount one filesystem on another machine, rsync for incremental backups, etc.

If what you need is to connect to the N900 through WiFi and transfer files from a laptop when you are not at home (begs the question why not use a cable), that's when you're faced with the choice between Ad-hoc mode (which takes some configuring at both ends), or with setting the computer up as an AP so the N900 can connect to it, or with setting the N900 up as an AP so the computer can connect to it.

Either way, though, get your TCP/IP networking right (you can ping from one host to another) before you try to do anything over that network...

There's maemo-pc-connectivity which allows you to setup adhoc and what not through it. Mind you this is a meta package meaning that you'll need to grab this and its dependencies to make it all work.

you can use TinySmbgui too