Question(s) about Drosophila Melanogaster

[tempust]

I'm doing the virtual fly lab in school, and to be honest I'm perfectly confused. Like, I have next to no idea what I'm doing.
Here's the website and the login info:
<www.biologylabsonline.com>
username: dhsapbiology01
pass: biology1

I have to mate the flies and follow them to the F2 generation, and answer a few questions and I'm totally lost:
1) Perform a dihybrid cross that demonstrates epistasis.
2) Identify one lethal trait.
3) Identify an X-linked trait.
4) Identify three linked genes and draw a linkage map for these genes.

And for each, I have to state the null hypothesis, draw out the punnett square used to derive the "expected" values, write out the chi-squared calculations that support the null hypothesis, and interpret the chi-squared calculations.
Gah.
Can anyone help me with anything here, anything at all? Even if you don't have time to give a full support, I'd really, really appreciate whatever I can get.

Here's some things I do know:
Bar-eyes is an X-linked dominant trait. I just don't understand how to "arrive" at that conclusion.
I think for the epistasis cross I was supposed to get something like eyeless and something else.

Sorry, I'm a mess. I'd appreciate SPEEDY responses, again, even if you can't give me everything!
Thanks so much!

[tempust]

Okay, I got the sex-linked trait (bar-eyes, X-linked dominant), as well as the lethal mutation (star-eyes) and all of the calculations and auxiliary information for both. But I still need the linked genes, as well as the epistatic genes....please help?