In Setup - Settings open the Symbol Libraries node and add a new library using the Add new button and browse to the location of the project file (if the dialog hasn't already filled in the location). This should set the path and Alias. Change the path to a . (dot/full stop character) but leave the alias as is. Make the library writeable and then press OK. Move the library to the top of the list using the arrows and then press OK.
Alternatively edit the project file (name.prj) and add the ". 'library alias'" to the IndependentLibraries section of the project file, use the same syntax for the alias as your other libraries. To make it writeable the format should be:
VALUE "DIR [W] . (Your alias here)"
For the first method: It does not allow me to type just "." as Name,
it says I should use letters.
About the second method, I completely did not get how to do it.. Where
should I edit the file, what should I open..?
Edit the project file associated with the schematic, the file ending in .prj.
. (dot) is not the name, rather it is the path. So if my project alias is preview my entry in Setup > Settings > Symbol Libraries would be:
I did not get any attachment..
The attachment should be with my previous response. But if you've not managed to resolve this by now you should contact your local support office.