Using a line in the php.ini file which will override 4Mb limit.

Hi there,

I need to upload a theme to my WordPress site but I get an error message which says: “The uploaded file exceeds the upload_max_filesize directive in php.ini”.
The limit for file uploads on the server that I am on is set to 4Mb.
Thus I created a php.ini file in the cpanel because there was none. I think that I need to add a line in the same php.ini file which will override the 4Mb limit. I’m not sure what the line should look like / say?
Am I going about the correct way?
Could someone please instruct me and tell me which line(s) I should add in my php.ini file?

Many thanks in advance!