Using Landsat images how do I create my own indices to extract particular landuse? Are there any tool/ software for creating indices?
I would start by manually labeling the pixels in an entire scene that are vs are not part of your desired landuse. Then you could try various predictive model formalizations to build models that predict the marked pixels, keeping the model that gives the best results. (There is an entire field of techniques called "model selection" that helps do this efficiently.)
Logistic regression using various combinations of bands, or a decision tree classifier trained over all bands, are examples of models that would provide an appropriate level of expressibility for an index.