MacBook Pro Computer :)

So DH bought me a new MacBook Pro computer. So far, I absolutely love it but am still struggling with how it works. Going from a PC to a Mac is a bit of a learning curve. I cannot figure out how to edit my photos yet so they all come out really huge. I want to download Irfan view but not sure it is compatible. It comes with a program called iphoto but I do not see anywhere in the program where I can edit the size of the pictures. I guess I will have to use the pc for pictures until I can figure it out. The only problem is I find the pc to be so so so slooooooow now. I seriously love the mac!