Choosing lanes

The experience gained by killing creeps and heroes are generally split between all the nearby heroes so if all the five heroes play from the same lane. Ones level will be stuck due to gaining of very less experience.

For Pub and simple games there are basically 2 heroes in top and bottom lane and 1 solo hero in mid.

For league and clan wars, Most of the clan prefers to choose two solo heroes in top and mid or mid and bottom and other three heroes in bottom/top lane. Most of the time from three heroes two of them will be roaming. This is not currently necessary for you who are just learning how to play.

Reasons

If you want to play solo you take a hero that makes difference in the pattern of games with its level and items. Some heroes make difference through items and some with levels. Since, you played solo your level you will be slightly greater that other heroes from top and bottom lane and your gold will also be rather better if you did a better lane control after you cross level 6 you are supposed to leave the lane and gank (ambush) opponent heroes in other lanes so you ally can establish a lane control. Controlling lane is to kill them or to make them distant from the creeps and also make them get less experience. Due to this your team will get upper hand.

Middle lane is considerably most easy lane to protect or defend oneself. The distance between two towers is short so it gives you more advantage to hide and defend yourself. There are also hills in middle lane so when a range hero try’s to attack an up-hill hero her will have 25% chance to miss an attack. And both runes which appear every 2 minutes are also nearby for the middle lane hero. So, there are many advantages playing in middle lane if you can farm and play well. Later, you will come to know which hero will be more suitable for middle lane usually like spell caster and Semi –carry heroes.

And while playing from other lanes you are more vulnerable of getting gank and their wont be any up-hill. Your another teammate will assist you in the lane and also their will be 2 enemy heroes rather than one. While playing in other lanes it is mostly recommended to play heroes who can perform great combo and show the a great team work. 

One of the most important things of laning is also prevent from dying which will be like feeding on gold and experience to your enemy. The best thing to do when you keep on dying is to just back up and gain experience and when their creeps comes to your tower then trying to get gold and also believing in your teammates. If you keep feeding your opponent heroes they will gain advantage and before you know the game will be over. If you feed your opponent many times they will also know that you are bad in playing and try to kill you more than any of your teammates.

Before you start playing in pub games it is better for you if you practice with AI which would make you gain experience on how to play and you will know the basics also. In DotA, every hero has their weakness like spell caster when used silenced upon them become useless. Weakness can also be covered up with the help of items. So, at first practice with AI for almost a month before you play with human players so you can be a good player otherwise you may lose your gaming spirit because of dying most of the times while playing with human players.

You may download AI maps from Get Maps