The standard maximum size of the file that you can upload in PHP is 2MB, but some scripts require an increase of this size.
Just create a file named php.ini in your computer and upload it to the folder of your web hosting, which you want to change the maximum size for:
upload_max_filesize = 10M
post_max_size = 20M
This will increase the maximum size of uploaded files in PHP from 2MB to 10MB. Note that post_max_size should be twice larger than upload_max_filesize.