How do I know, if I am playing sharp or not?

I recently was reading about playing sharp. Assuming, a situation demands that I should play sharp - how can I know that I'm playing sharp or not?

Considering your rating and the fact that you dont know what "sharp play" is, I wouldnt worry about it.  At your level its not going to matter.

Pity, that answer wasn't productive at all. All it did was pollute the forum.

Wasnt personal, but it wont matter at your level.  It doesnt matter at my level, so im in the same boat.

Seriously? Go back to Reddit please. 
Just playing more and more games certainly helps. If you analyze your games and look for forks, pins, or any other moves with <+1 or so, you should get an idea of what "sharp play" looks like. This is coming from a person with 1 game on this site though, so take it with a grain of salt. 

Reddit?

Decades ago, there were a number of books with a considerable amount of material devoted to the explanation of chess terms. I am not aware of any recent book like that, but I think this passage conveys some indication of the meaning of "sharp".

"... Openings such as the Blackmar-Diemar Gambit, Albin Counter-Gambit, Latvian Gambit, etc., are all played regularly at club and league level, ... there is much to be said for playing such systems at lower levels of play, particularly if you enjoy playing sharp attacking lines.  Many players find it uncomfortable to defend against an opponent who is prepared to sacrifice material in return for speculative attacking chances. In such positions, the cost of a single error is much higher than in quieter openings. ..." - FM Steve Giddins (2003)

I don't think that sacrificing-for-attacking-chances is the only way to play sharply. There are all sorts of risky things one can do while seeking to attack: not bothering to castle, castling and then advancing the pawns in front of one's king, putting one's queen on h3 while there is an enemy bishop on c8, etc. It seems to me to be desirable for a player to have some degree of awareness of this sort of issue.

"... it is not unusual for a player to seize a long-term strategic advantage in return for piece activity or a lead in development. In this case the player with the better development has taken on an implicit commitment to undertake rapid action. Advantages such as a lead in development are inherently temporary, because when the opponent has brought out all his pieces the advantage disappears. A common mistake is to take on such a position, but not to appreciate that the long-term chances lie with the opponent The result is a fatal lack of urgency. ... At the end of the opening, ... [if one player has the better long-term chances, the] strategy for the two players may be quite clear: one side must aim to consolidate and contain his opponent; the other must play to stir up trouble quickly. ..." - GM John Nunn (1998)

It is just a subjective term, really.  Its like saying someone is playing accurately or has good calculations or brilliant tactics or whatever other words.   They are just words.    You want to know if you are playing well?  Consistently win or draw vs higher rated players.  That is the only measuring stick that really matters, in the end.  Well, that and having fun with it all.   

You will know that you are not playing sharp if you keep on losing each game you play.

 If you are better at shorter games than long ones, you are likely sharp, also if you have a higher tactics rating than your other ratings

To begin to learn about attacking, one might try Simple Attacking Plans by Fred Wilson

https://web.archive.org/web/20140708090402/http://www.chesscafe.com/text/review874.pdf

https://www.newinchess.com/Shop/Images/Pdfs/7192.pdf

or Starting Out: Attacking Play by James Plaskett.

https://web.archive.org/web/20140708101549/http://www.chesscafe.com/text/review467.pdf

ask your opponent