You can send pictures (or any files, for that matter) by using your email provider's web interface. You just log in, create a new message, and attach the files.
The message you get about installing an email program is about making it possible to send an email (with or without attached files) from your computer, without using a web browser at all.
The operating system makes it possible, that whenever you want to "send picz", you can do it in a quite simple way, because of the association of the email sending function with the email sending program. (Sorry can't be more clear than that.)
And of course, if you want to, you can install an email sending program, for example Mozilla Thunderbird, or Windows Live Mail (or watchamacallit) configure to use it with your email provider's email sending settings, and then you'll be able to use that feature.