Switch Discs on ePSXe?

for example FF7...disc1 is done its time for disc 2 but...i cant switch from disc 1 (rom) to disc 2 (rom)
how do you do that?
i dont have memory card also...
and what is a memory card(psx) for a pc?sorry if this is already done..:(

Memory card for ePSXe is automatically created when you first using it.It is stored in the memcard folder in your ePSXe directory.For changing disc,
Just go to "File" --> "Change Disc" --> "ISO"
and choose the .iso file.