How can Create the xml sitemap..?

You can easily create an XML Sitemap in WordPress with the Yoast SEO plugin, which is also a great SEO plugin that you should have on every website.

XML sitemaps can be created using various sitemap generators. It is a coded sitemap used to submit in webmaster tool to help spiders crawl them and index the webpages in search engines.

Try A1 Sitemap Generator for Windows and Mac
http://www.microsystools.com/products/sitemap-generator/

Here are some steps for creating XML Sitemap :
Open up the SEO Spider, type or copy in the website you wish to crawl in the 'enter url to spider' box and hit 'Start'.

1. Crawl The Website
2. Click 'Sitemaps > Create XML Sitemap'
3. Select 'Pages' To Include
4. Exclude Pages From The XML Sitemap
5. Choose The Last Modified Date
6. Select The 'Priority' of URLs
7. Select The 'Change Frequency' of URLs
8. Select Images To Include In The Sitemap
9. Click 'Next' To Generate The XML Sitemap
10. Submit Your XML Sitemap To Google