How to set the parameter values for ARX model

Hi all,

There are two time series, "A"(auto-regressive variable) and "B"(exogenous variable).

Please let me know how to estimate the parameters for auto-regressive variable by fixing the parameters for exogenous variable. Such that,

First set the parameters for exogenous variable and then find the parameters for auto-regressive variable

Thanking you in advance,

Kushan

[Kushan]

Experts please !!!!!!1