I want to change my RB411 OS from FirePro RouterOS 4.3 to MikroTik RouterOS. How can i done this.

"Firepro" is just a branded version of MT ROS. You can upgrade it the same as any routerboard.

If you use netinstall, you can go straight to 6.7. Otherwise, upgrade to 4.17 => 5.26 => 6.7. Be sure to check and update the firmware along the way. You might also need to update the license before/after upgrading to 4.17.

if you netinstall it the branding will be replace with the default mikrotik

I need Netinstall tutorial.

"Firepro" is just a branded version of MT ROS. You can upgrade it the same as any routerboard.

If you use netinstall, you can go straight to 6.7. Otherwise, upgrade to 4.17 => 5.26 => 6.7. Be sure to check and update the firmware along the way. You might also need to update the license before/after upgrading to 4.17.

I need netinstall tutorial.

http://wiki.mikrotik.com/wiki/Netinstall

HTH,