Hello…
I want to perform backcross for my mutant before checking phenotype.
Could you please let me know the procedure of the crossing?
What is the difference between backcross and outcross?
thank you in advance 
At Koelle protocols there is a “Gene knockout protocol”.
It says how to make mutants and how to backcross them.
http://www.med.yale.edu/mbb/koelle/protocols/protocol_Gene_knockouts.html
I guess backcross and outcross is the same, depending on the translation.
Good luck, backcrossing takes a lot of time!
The definitions that Google links to are pretty good:
tr.v., -crossed, -cross·ing, -cross·es.
To cross (a hybrid) with one of its parents or with an individual genetically identical to one of its parents.n.
The act of making such a cross.
An individual resulting from such a cross.
tr.v., -crossed, -cross·ing, -cross·es.
To cross (animals or plants) by breeding individuals of different strains but usually of the same breed.n.
The process of outcrossing.
Offspring produced by outcrossing.
So, if you have a deletion mutant isolated from mutagenesis of N2 and you cross the mutant back to N2 any number of times you’ve backcrossed it. If you cross it to another strain (say, an Unc so you can easily spot cross-progeny, or a strain containing a balancer chromosome), that’s an outcross.
There is an excellent guide to genetic mapping in C. elegans called Worm Breeding for Dummies. You can find it here:
http://www.colorado.edu/MCDB/HanLab/WBFD.PDF
Its revised and expanded version is also available in WormBook:
http://www.wormbook.org/chapters/www_introandbasics/introandbasics.html
Igor.
Thank you so much. 
Phetdee