Here are two steps to add your own path to matlab search path permanently.

addpath your/path
savepath

help of the two command in matlab:

savepath

savepath saves the current MATLABPATH in the pathdef.m
which was read on startup.

savepath outputFile saves the current MATLABPATH in the
specified file.

savepath returns:
  0 if the file was saved successfully
  1 if the file could not be saved

addpath

 addpath DIRNAME prepends the specified directory to the current
 matlabpath.  Surround the DIRNAME in quotes if the name contains a
 space.  If DIRNAME is a set of multiple directories separated by path
 separators, then each of the specified directories will be added.

 addpath DIR1 DIR2 DIR3 ...  prepends all the specified directories to
 the path.

 addpath ... -END    appends the specified directories.
 addpath ... -BEGIN  prepends the specified directories.
 addpath ... -FROZEN disables directory change detection for directories
                     being added and thereby conserves Windows change
                     notification resources (Windows only).

 Use the functional form of addpath, such as addpath('dir1','dir2',...),
 when the directory specification is stored in a string.

 P = addpath(...) returns the path prior to adding the specified paths.

 Examples
  addpath c:\matlab\work
  addpath /home/user/matlab
  addpath /home/user/matlab:/home/user/matlab/test:
  addpath /home/user/matlab /home/user/matlab/test