Each Member Nation has one vote in the General Assembly and every vote is equal. Decisions of the General Assembly on important questions shall be made by two-thirds majority of the members present and voting. These questions include recommendations on peace and security, election of members to organs, admission, suspension, and expulsion of members and budgetary matters. Decisions on other questions are reached by a simple majority. Most resolutions are adopted without a vote. A recorded vote must be requested before the voting is conducted.

A detailed description of the voting procedure can be found in the Rules of Procedure of the General Assembly. 

The Assembly may make recommendations on any matters within the scope of the UN but the resolutions are not binding on the member states. They carry, however, the weight of world opinion as well as the moral authority of the world community. and all member states have an obligation to act in cooperation with the United Nations. 
The so called "decisions" taken by the General Assembly are binding. The are dealing with matters internal to the United Nations such as budgetary questions, and the apportioning of contributions of member states to the UN regular budget.