i want to customize my default buddypress theme…

This is a big ask, you will need to have a look at css, as most of this can be coded here.

ok..thanks for your reply ….but i dont know where to change code and what to write to change my headr…

Files are in .css However you would best download a theme to local and experiment here first So that you become accustomed to css before changing any live theme or set up a subdomain and try there.
As for speed this is a combination of caching, optimizing, i.e. images,css,js minify,moving files, ie.css to head, js to foot, using cdn the list goes on. Why not try a good cache plugin to start with.

ok….thanks…..loughcorrib…i already use w3 cache plugin but it works well when my site is small but when member increase then they goes slow….
can i achieve facebook like fast loading without entire page loading??/

Bahadursinh
I had a look at your site on link you provided,it is a fresh install with no content ?? Is that the corect url you have above ??
As for w3 cache an excellent plugin with the proviso that it is correctly implemented on site. I would encourage you to go to plugin site and read more there. Then return and we will see can we take this a step further.

yes….provided link now contains fresh install of wp.now,i install bp on my new sub domain https://www.m.be-buddy.com for experiement..
now,i want this customization on that install..can you help me….>>how can i??
1:want to reduce height of header.

2.want to change the color of the theme not background.(default is white)

3.want to include the feature like facebook..means in facebook when user click on any link then certain part of the whole page is load not entire page is load..

4.want to make super fast in loading time…

5.want to change the height and color of top static navigation bar(admin link) of site.

6.want to display all the info like activity,profile,message,friend,group to be display on sidebar in vertical style not in default horizontal style..

Ok you have a lot of reading to do first start here,w3c to work on your stylesheets.