sql server - Role assignments in SSRS -

i have created ssrs report. in report viewer saw 2 security sections

1. site settings
2. folder settings.

what difference between these two?

i have give access 2 types of users

1. somebody having permission viewing report.
2. somebody having permissions view reports, upload report , modify datasource , parameter properties in report.

what should security roles should select adding these users?

first add user :

goto :
1) sitesettings-->security , click newrole assignment

2)enter group or user name , select role based on requirement. please see below screenshot.

then click on ok button. here can see list of roles assigned group or users.

3) click on link of home , click on link of folder settings.

4) see results following.

5)then click on new role assignment , see below screenshot.

6) in screen enter group or user name , select roles , click ok users

note:
1)somebody having permission viewing report.
to see reprot==>select browser role only
2)somebody having permissions view reports, upload report , modify datasource , parameter properties in report.
select "the publisher role" , "my reports role" them