Floating point arithmetic and conversion

Currently i am having problems dealing with floating point data. How to do the arithmetic and conversion by using the megafunction in the quartus 9.0 since i cannot implement it in my code? Sorry, i am just a beginner in vhdl design.

Besides, i found some packages from a guy named david bishop. However, i try to test the functionality of those packages, it seems unsynthesizable. Another question is if i compile a library in Modelsim simulation software , may i declare it in quartus ii software ?:confused: