I am having a problem uploading images to the stages on one of my pages. There is a fatal error in memory on line 23 of (phpGD) file, but on that line I have a getting image size situation, but I don't know how to fix it. Anyway, is there a way to fix this error?

Do you have the actual error message? If the message is it ran out of memory space not much you can do apart from up the php memory limit.

I was wondering how can I fix it, when I don't know where to increase the memory size?

In php.ini
the setting is called 'memory_limit'

And if you don't have access to php.ini you can try the following in .htaccess:

php_value memory_limit 64M

64M should be enough but change it to something bigger if you have the RAM (or just scale-down the image before you upload it).

Thank you for your response. I will try it if I have access to it.