Basic-Usage.md

 How to use BMB in just several lines of code?
 
-###Create BMB
+### Create BMB
 
 Add BMB in .xml file.
 
@@ -55,7 +55,7 @@ Or in .xml:
 app:bmb_buttonPlaceEnum="buttonPlace_sc_3_3"
 ```
 
-###Add Builders
+### Add Builders
 You have set attributes for BMB itself, now add builders for customizing boom-buttons to BMB. There are 4 different builders for the 4 kinds of boom-buttons above. For instance, use `SimpleCircleButton.Builder` for `ButtonEnum.SimpleCircle`. Click the links for 4 kinds of buttons above to find out how to use builders.
 
 ```
@@ -67,7 +67,7 @@ for (int i = 0; i < bmb.getButtonPlaceEnum().buttonNumber(); i++) {
 
 And now your BMB is ready for a boom.
 
-###Attention
+### Attention
 You must keep the number of piece-place-enum, number of button-place-enum and number of builders being the same. 
 
 The name of piece-place-enum is XXX_N_M, where XXX is name(DOT or HAM), N is number and M represents different types. Similarly, the name of button-place-enum is YYY_N_M. You must keep the first N equals to the second one. But you needn't keep the two M same(The code above is an example: DOT_3_1 and SC_3_3).