hc4361, user of Windows 7 woke up this morning with icon on their task bar saying 'Get Windows 10'. I know I did and others have got it.
Yansee, Windows 10 is NOT available yet. This is a "teaser" from Microsoft to get people show their interest.
Windows 10 will probably not come out till July or August.
If you are happy with Windows 7 then don't be pressured into upgrading to Windows 10 (when it comes out). It is free, but there are always problems with any new release of Windows.
I would wait at least 3 months after Windows 10 comes out before upgrading (if you want to) to let them iron out the problems.
Note the upgrade to Windows 10 will be free for Windows 7 and Windows 8 users.