See the First Login Howto page for the full dissertation. Long story short, you can gain access to your router using the:

• using Telnet (if you haven't already set up a password)
• via SSH (employ PuTTY or WinSCP or ..); use the password you set during First Login

• if there is no WebUI (Web user interface) in the image, you can swiftly install one following this HowTo: LuCI
• for other WebUIs have a look at the webinterface.overview
• You should make a backup for the day, that may never come

* To configure please read the wiki for the Unified Configuration Interface

• get Internet Connection up and working

Please note: (HTTPS access is only available after First Login)

If you feel insecure about the command-line interface, see if CLI helps you. For help with installing packages, see OPKG Package Manager

What you could/should do after flashing OpenWrt:

• As a precaution you should secure the access to your router
• Configure the packet filter with UCI: firewall or without it: netfilter
• Configure the packet scheduler with UCI: QoS or without it: packet.scheduler
• To configure your hardware buttons (if your device has any), see hardware.button
• If you have one or more USB ports, see USB
• If you have no USB ports, no problem, you can still mount remote filesystems
• If you want to monitor the connection status to the Internet, you should access your modem
• To understand, then enable and configure the wireless, consult wireless.overview.
• enable and configure your crond

• install some web server: http.overview

• setup a vpn link
• install (and configure) Asterisk: voip.asterisk
• connect a USB webcam or a USB TV card: usb.video

You find many more HOWTOs and Technical Reference here: Documentation. The project OpenWrt and its Wiki are maintained by volunteers. You are cordially invited to contribute.

→ generic.failsafe

→ generic.sysupgrade

→ generic.debrick