Need help for upgrade a IM1.4.0

Hi All,
I have a 6 years old IM1.4.0 site with some mods installed running on MySQL 4x.
I am facing some problems with the site & want to upgrade it to IM latest version.
Can anyone tell me what I have to do to put the site to latest version, and how to get this done?
Thank you.
I have a 6 years old IM1.4.0 site with some mods installed running on MySQL 4x.
I am facing some problems with the site & want to upgrade it to IM latest version.
Can anyone tell me what I have to do to put the site to latest version, and how to get this done?
Thank you.