How can I get visitors from others countries?..... Geo-location global in google webmasters.
As for search engines, a site is always located in one country only. The location depends either on the ccTLD of the site (.ca, .co.uk,....) or, if the site has an international TLD (.com, .info,...) , on the location of its IP (hosting) with still the opportunity to choose another country in your google webmaster account.
I understand you did not select a country as geolocation in google webmaster, then your site is located in the USA (not India) because your site has been hosted in the USA.
If the USA is your main country target, this is OK.
visitors from others countries like... UK, Australia, Germany
If your main target is UK (or Australia), you have to select UK (or Australia) as geolocation in google webmaster.
, people in Germany speak German. Your site in English may get visitors from Germany, but it cannot get huge amounts of visitors from Germany because people in Germany search mainly (not always of course) with keywords in German within sites in German. So don't expect to get huge amount of visitors from Germany. Similarly for all non English speaking countries.
performing well and our all major Keywords ranking top
As stated above by other, this single fact is not very relevant. You have first to check the popularity of those keywords. Google has some tools which show how popular a keyword is. If your keywords have a low popularity, you cannot get huge traffic. You must then change your keywords
what are recommendation for solve this problems.
If your geolocation (USA) is OK for you and if your keywords are popular, then the problem may arise from your site content (your site may be not/not enough/too much optimized on your keyword) and/or from your backlinks.
I had a look at your backlinks: The anchor text of many of your backlinks is "Aegis Software" and to a lesser extend "java developers". This is perfect if they are your main keywords. But this does not help you with regards to your other primary keywords such as "software development" and other ones. So I strongly recommend you to get backlinks with your keywords as text anchor.
More generally, I suggest you to search and get more quality backlinks. If you are looking for a global English-speaking market, you need quite a lot of quality links because competition is hard.