how can i access the pdf on my computer through my phone

To share files amongst your devices is simple to do.

When the file is open, go to the top left corner and click on the "cloud" icon with an arrow piercing the bottom.

Depending on the size of the document, be sure to give it time to upload and then download it to your other devices. 

Among the cool things about this is that if you stop reading on one device on (say) page 53, you find the other device will open the document to page 53.