Hello everyone,
If you want to create a SubSite under site collection through code use following code. This will help you to create brand new SubSite under your site collection, my given code will create a "blog" site under the site collection that you created earlier.
Code:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Microsoft.SharePoint;
using Microsoft.SharePoint.Administration;
namespace CreateSubSite
{
class Program
{
public const string siteUrl = "http://myserver:5263/sites/Training"; //url_Of_your_WebApp
static void Main(string[] args)
{
SPSite site = new SPSite(siteUrl);
// Create new subsite of type Blog here-> 1033=us-eng site type=BlOG#0
SPWeb web = site.AllWebs.Add
(
"BlogSiteUrl",
"Blog Site",
"Some Blog relevant information",
1033,
"BLOG#0",
false,
false
);
Console.WriteLine("Blog site has been created.");
Console.ReadKey();
}
}
}

Two Ways to create subsite:
- Go to site content select new Subsite and fill all the details click create this will create a subsite for you.
- Use Visual Studio via C# language
- Use PowerShell
For PowerShell --> Open SharePoint 2013 Management Shell and use following Script:
PowerShell command for creating subsite:
$template = Get-SPWebTemplate "STS#0"
New-SPWeb http://dsknomoe12:5566/subsite -Template $template

Subsite created successfully.........
Subscribe my blog...........