Assistance with the back-end of a website

Hello, I have a website almost ready in front-end (i will need some help in the download page and in index for one box) and i want help in back-end. My site has written in php and some javascript, and i want someone with that knowledge. My site is a web app. I have a form with some choices and i want to fix the functionality of the buttons . I have an multi drag and drop upload button that i want from u to fix it because after that i added to my template, it didn't work. I want also to fix the download page, that the user will have the opportunity to download some specific files that my web app create from the upload files. I have also an email form ready in front-end, but i have problem also in back-end, and i want from u to see why it didn't send the e-mail, and to fix it! I'm a programmer too so, i'm waiting from u reasonable and serious proposals. I don't believe that is a lot of work. Contact me for more explanations!