To be honest its not simple, it also depends what type of o/s you are using i.e.
Windows Vista, XP, 7 or as i do Mac.
You will need the website domain name, username, password and then you will probably need to use an FTP program to upload the images or pages but you have to put them in the correct place on the web server or the links and pages wont work.
Some web hosts do provide a file manager which will allow you to upload images from your pc onto your website.
This is a brief outline, it can be tricky, i have been doing it for years on and off and i still make mistakes and my website does not work until i figure out the problem.
Unless you know what you are doing i would suggest learning about web site creation and uploading images, you need to understand what happens when someone clicks on a hyperlink, and if you want to create thumbnails which will open up a larger picture you have to create two sets of images.
Also when uploading photo's you really need to optimise them for the web i.e. reduce the number of colours, use a web friendly format, ie tiff or jpg.
i could go on for ages.
Not trying to put you off, but i think you will get the message its not that simple.
