New Category.

I want to add my site in a specific regional category. But that category does not exist. I tried my best but did not find suitable category. What I need to do. Does I need to contact the editor?

The answer depends a little on where in the directory the category would be - which category were you looking for, specifically?

In fact I want to add "Real Esate Projects" under this category,
http://www.dmoz.org/Regional/Asia/Pakistan/Business_and_Economy/Real_Estate/

The purpose of this category is to hold Real estate projects under constructoin.

Within Regional we list RE wesbites in the locality were they are fysicly located.
Only websites with projects all over Pakistan would be listed in the category you mentioned.
If you want to suggest such a site please suggest it to the mother category (the link your provided). When we have enough sites with projects we might create a sub-category for them.
If you want to suggest a site with a project in 1 city please suggest it to the RE cat for that city.
If you want to suggest a site with projects in several cities in 1 province please suggest it to the RE cat for that province.
If a city or province does not have a RE cat please suggest the site to the corresponding Business and Economy category, and when there is no B&E cat please suggest the site directly under the city or province.

I want to suggest a site with a project in 1 city under http://www.dmoz.org/Regional/Asia/Pakistan/Business_and_Economy/Real_Estate/,
Because it is a real estate project.

But city does not exist. What I need to do?

Please find the right province under http://www.dmoz.org/Regional/Asia/Pakistan/Provinces/ . Some of the province categories, for instance Punjab, have locality categories. If there is a category for the locality (that is, the city), please suggest the site to that category. If there is no category for the city, please suggest the site to the right province.

Thank you!

www.dmoz.org/Regional/Asia/Pakistan/Provinces/Islamabad_Capital_Territory/Business_and_Economy/
.There Real Esate category does not exist. Does I need to request to open new category under this?

We don't create categories on external request; we create them when we have enough websites to justify their creation.

Please, just suggest your website to what would be the parent category. If you suggest a few competitors to there as well, the subcategory might be justified.

As nea suggested: Suggest the site to the closest possible category. We will by ourselves create subcategories when enough sites are available. No need to worry about caegory creation for you.

<this time I was to slow>