Unfortunately, this question is a bit too broad to answer completely. There are so many imaginable situations in which a young widow in the Song dynasty might live, and it would simply take too long to cover everything. So I hope you’ll forgive me for keeping this response brief.

Is there any work for women like me to do?

Of course! Depending on various factors, ranging from the widow’s assets (property, dowry, etc.) to her social status, she might either work at home, or outside of the household. In a poor, farming household, a widow might be expected to aid family members in the various labours involved in land cultivation. It was quite common for women to make textiles at home, with homegrown silk or cotton; even in wealthier families, many women would spin or weave. These skills gave widows the opportunity to earn an income. Outside of the home, more opportunities were available for widows in large cities, where they could establish and/or work in: food stalls and restaurants, wine shops, embroidery businesses, courtesan-work, and so on.

Or, will there be someone to provide for me?

Typically, a surviving male member of the household would take on the responsibility of providing for a widow, but this did not mean that a widow would not do any work! Textile production would continue to be a means of support for the family, alongside other sources of income. A widow would also have access to her dowry, which may have been a substantial amount of money, depending on the circumstances.

If I want to marry again how would I do that?

A widow could use her dowry to attempt to re-marry, and might receive the assistance of her family in finding a husband. The rise of Neo-Confucianism brought with it an emphasis on venerating women who chose not to re-marry out of loyalty to their deceased husband and his family. However, in most cases these women, who acted as shining exemplars of virtuous women in a Neo-Confucian context, existed largely on paper. In practice, every widow encountered unique circumstances and situations, and for most widows, emulating the Neo-Confucian ideal was not a priority.

I do apologise, again, for my brevity. If you want more information about widows in the Song, check out the work of Patricia Ebrey, Beverly Bossler, Hill Gates, Bettine Birge, and Linda Walton.

This actually would have been one of the best times in the imperial period to be a widow. She would have significant rights to whatever wealth her husband may have accumulated, and would have very little societal resistance to using that wealth to build new capital.
The estate/commercial rights of women reached their apex in the song. But these rights would be challenged by neo Confucian elites. When neo Confucian orthodoxy took hold in the Yuen period, women's rights began to take a regressive path that continued strait through to the 20th century, only shattered, like everything else, by the revolution.