If I remember correctly the simplest thing is to open a terminal and type "redhat-config-language" this should give you the option to select which language you want to use by default if you already selected additional languages in the installation procedure.
If only the current laguage shows in the dialog, you'll need to get the additional RPM's for full support of each language you need, this site has some useful information
http://www.ficorp.com/linux_i18n.html It doesn't however mention Lithuanian!
I think KDE makes the configuring of language support more like the faciliies used in Window$. In my Fedora setup, I simply right clicked on a clear patch on the menubar and added a special button > Preferences (or you can open Control center from the Menu and in the region settings define your preferred and alternate language support. then set up your keyboard and choose keyboard layouts to use with the languages you have chosen - if that's what you use...
Hope that helps, all the best